This invention relates generally to error correction and detection in a digital communications system, and more particularly to coding digital transmission of short messages including interleaving and convolutional coding for burst error correction, and cyclic block coding for error detection with minimal compromise in signalling sensitivity.
Convolutional coding is a known technique for error correction, and several methods are available for its implementation. Such methods are discussed in the system described in U.S. Pat. No. 4,055,832 issued Oct. 25, 1977, to John En, which is assigned to the same assignee as the present invention.
Burst error correction may be accomplished by known methods, such as, for example, methods utilized by the system described in U.S. Pat. No. 3,882,457 issued May 6, 1975 to John En and also assigned to the assignee of the present invention.
Cyclic block coding is a known coding technique that is extremely well suited for error detection as described in W. W. Peterson and D. T. Brown, "Cyclic Coding for Error Detection", Proceedings of the IEEE, Vol. 49, at pp. 228-35, (January, 1961); and W. W. Peterson, "Error Correction Codes", the MIT Press, Cambridge, Massachusetts, and John Wiley, New York (1961). Some methods for implementing cyclic block codes are also available to those skilled in the art, as described in Shu Lin, "An Introduction to Error Correcting Codes", at pp. 70-83, Prentice Hall, Englewood Cliffs, New Jersey (1970).
The use of bit interleaving in conjunction with a Hamming code for correction of burst errors is disclosed in a presently pending U.S. Patent Application, Ser. No. 7,086, filed Jan. 29, 1979, now U.S. Pat. No. 4,229,822, issued Oct. 21, 1980, by Steven Bench, and which is also assigned to the assignee of the present invention.
Techniques for using cyclic block codes for short messages and resolving the inherent synchronization problem by combining the block codes with an autosynchronization sequence is disclosed in a presently pending U.S. Patent Application, Ser. No. 51,938, filed June 25, 1979, now U.S. Pat. No. 4,271,520, issued June 2, 1981, by Daniel J. Coombes et al, and which is assigned to the assignee of the present invention.
While most of these separate techniques are known and general in their application, it has not heretofore been known that they would be combined into a single coding scheme having non-complex implementation and broad application to coding of short messages, without losing the effectiveness of each individual technique or compromising the signalling sensitivity of the resultant communication system.